In situ combustion (ISC) processes are applied for the purpose of recovering oil from light oil, medium oil, heavy oil and bitumen reservoirs. In the process, oil is heated and displaced to an open production well for recovery. Historically, in situ combustion involves providing spaced apart vertical injection and production wells within a reservoir. Typically, an injection well will be located within a pattern of surrounding production wells. An oxidant, such as air, oxygen enriched air or oxygen, is injected through an injection well into a hydrocarbon formation, allowing combustion of a portion of the hydrocarbons in the formation in place, i.e., in-situ. The heat of combustion and the hot combustion products warm the portion of reservoir adjacent the combustion front and drive (displace) hydrocarbons toward offset production wells.
One difficulty associated with applying in situ combustion as a stand alone recovery method in heavy oil and bitumen reservoirs is the lack of mobility of the oil. For example, in situ combustion involves the injection of an oxidant into a formation. The oil in place serves as a fuel for the combustion front once ignition has occurred. As with any burning process, heat, oxygen, and fuel must be readily available to sustain combustion. In heavy oil and bitumen reservoirs this process is interrupted by the fact that the oil in the reservoir is not mobile. Therefore, combustion gas products (CO, CO2, H2S, etc.) and mobilized oil can become trapped in the reservoir which leads to the suffocation of the combustion front. Therefore, a need exists for a method of initiating enhanced communication between the injection and production wells along with a method for extracting both oil and gas from the reservoir for in situ combustion processes.